DE60119429T3 - Portable four-stroke engine - Google Patents

Description

BACKGROUND OF THE INVENTION

FIELD OF THE INVENTION

The present invention relates to portable four-stroke engines which are mainly used as drive sources for portable power machines such as trimmers. In particular, it relates to an improvement of a four-stroke engine according to the preamble of claim 1.

DESCRIPTION OF THE PRIOR ART

Such a portable four-stroke engine is already known, such as in the US-A-5,988,135 is disclosed.

Of course, four-stroke portable engines are useful in that they avoid environmental pollution as well as ensure the health of the operator since the exhaust gas is relatively clean. However, since the structure thereof is more complicated than that of two-cycle engines, there is a disadvantage that it is difficult to reduce the weight thereof. Weight reduction is an important issue for improvements particularly in the usability of portable four-stroke engines.

However, in the portable four-stroke engine disclosed in the above-mentioned patent publication, a valve operating mechanism for opening and closing the intake and exhaust valves provided in the upper part of a cylinder head is of a type including pushrods and rocker arms, and one Valve actuating chamber for receiving the push rods, a cam shaft for driving the push rods, etc. is formed in a side wall of the engine main body; The size of the engine main body therefore inevitably increases, making it difficult to reduce the weight of the engine.

SUMMARY OF THE INVENTION

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a lightweight portable four-stroke engine having good operability by making the engine main body compact.

According to a first feature of the present invention, a portable four-stroke engine according to claim 1 is proposed for achieving the above object.

The above-mentioned power output mechanism corresponds to the centrifugal clutch described in the following embodiments.

According to the above-mentioned first characteristic, because the timing gear and the power output mechanism are mounted on each side of the cylinder head at the both ends of the crankshaft, the balance at the both ends of the crankshaft is improved, the center of gravity of the engine can be as close as possible be formed on the central part of the crankshaft, which together with the reduced weight can improve the usability of the engine. Further, since the loads generated by the timing gear and the drive shaft, during operation of the engine separately act on the two ends of the crankshaft, so as to avoid that the load on the crankshaft and its bearings is located, the Life of the same can be improved.

Further, the valve operating mechanism includes the timing transmission, which is disposed outside the engine main body and connected to the evern end of the crankshaft, and a cam system for transmitting the rotational force of the output side of the timing transmission to the inlet and outlet valves for opening and closing forces, wherein a first valve actuating mechanism chamber The timing gearbox accommodating the timing gear is integrally provided with an oil tank disposed outside the engine main body on the same side as the timing transmission, wherein a second valve operating mechanism chamber accommodating at least a part of the cam system is formed in the cylinder head, and wherein one pair of oil slingers for mixing and atomizing oil stored in the oil tank to generate an oil mist to be supplied to the second valve operating mechanism chamber and the crank chamber, on the crankshaft i n are mounted in such a manner that the timing gear is disposed between the pair of slings.

Since the oil tank is disposed on a side outside of the engine main body, the overall height of the engine is greatly reduced. Further, since the timing gear receiving first valve actuating chamber is provided integrally with the oil tank, a part of the gear housing is accommodated in the oil tank to make the engine even more compact.

Further, since the lubricating system of the valve operating mechanism is divided into two parts, that is, a part for lubricating the timing gear within the first valve operating chamber with the oil spouted inside the oil tank, and a part for lubricating the cam system within the second valve actuation chamber with the oil mist generated within the oil tank, the load exerted on each part of the lubrication system is reduced and the entire valve actuation mechanism is carefully lubricated.

Furthermore, the pair of oil slingers are fixed to the crankshaft with the timing gear interposed therebetween, whereby the oil stored within the oil tank can be agitated and splashed by the timing transmission without hindrance regardless of the operating position of the engine, and the oil mist can be effectively generated.

According to a second feature of the present invention, in addition to the above-mentioned first feature, there is proposed a portable four-cycle engine in which a flywheel is mounted on the crankshaft between the engine main body and the power output mechanism, the flywheel comprising cooling blades for conveying cooling air to the engine main body and a flywheel larger diameter than that of the power output mechanism has.

According to the above-mentioned second feature, the cooling air can be suitably supplied to the engine main body without hindrance from the power output mechanism by rotating the cooling blades, while minimizing any increase in the size of the engine due to the flywheel, and the cooling property thereof can be improved.

Further, according to a third feature of the present invention, in addition to the above-mentioned first feature, there is proposed a portable four-cycle engine in which a through hole through which the oil mist generated in the oil tank is supplied to the crank chamber is provided in the crankshaft and an open end of the crankcase Through hole is arranged in the oil tank between the timing gear and an oil spinner.

According to the above-mentioned third characteristic, the open end of the through-hole of the crankshaft can be located in or near the central area of the oil tank without hindrance from the timing gearbox or oil spinner, and it is possible to prevent the oil stored within the oil tank Oil penetrates directly into the through hole.

Further, according to a fourth feature of the present invention, in addition to the above-mentioned first feature, there is proposed a four-cycle portable engine in which the oil tank for storing lubricating oil and the timing gear of the valve operating mechanism are disposed on one side of the engine main body, the timing transmission being in the oil tank wherein a timing tube receiving the timing gear is integrally provided with the oil tank and wherein the open end of the belt guide tube protrudes inside the oil tank toward the middle part of the oil tank, so that the open end regardless of whether the engine is upside down or is located on the side, above the liquid level of the stored oil.

According to the above-mentioned fourth feature, the overall height of the motor can be reduced, while at the same time any increase in the width of the motor can be minimized, and the motor can therefore be made more compact. Further, since the open end within the oil tank of the belt guide tube accommodating the timing gear is always above the liquid level of the stored oil, even if the engine is disposed upside down or on its side, preventing the stored oil from closing the timing gear flows together, wherein an oversupply of oil for the timing transmission can be prevented and at the same time the amount of oil stored in the oil tank can be maintained at a predetermined level.

Further, according to a fifth aspect of the present invention, in addition to the above-mentioned first aspect, there is proposed a portable four-cycle engine comprising an oil tank, an end of the crankshaft extending into the oil tank, and the timing gear of the valve operating mechanism connected to the crankshaft within the oil tank. are arranged outside of the engine main body on the opposite side of the power output mechanism and the timing gear is lubricated by the oil within the oil tank.

According to the fifth characteristic mentioned above, it is not necessary to provide a special chamber for housing the timing gear in the side wall of the engine main body itself, the overall height of the engine can be reduced due to the lateral arrangement of the oil tank, the side wall of the engine main body can be thinner in this way be made more compact and the weight of the entire engine can be greatly reduced. Further, the balance at both ends of the crankshaft is improved by disposing the power output mechanism on one side of the engine main body and disposing the timing transmission and the oil tank on the other side, with the center of gravity of the engine as close as possible to the central part of the crankshaft can be, which, together with the reduced weight, increases the manageability of the engine.

Further, since loads arising from the timing gear and the power output mechanism during operation of the engine separately act on the both ends of the crankshaft to avoid locating the load on the crankshaft and its bearings, the life thereof may be increased.

Further, since the timing gear is lubricated directly with oil inside the oil tank, the lubrication system can be simplified.

According to a sixth aspect of the present invention, in addition to the above-mentioned fifth aspect, there is proposed a portable four-cycle engine, wherein a cooling fan is fixed to the crankshaft between the engine main body and the power output mechanism, the cooling fan having a diameter larger than the power output mechanism.

According to the above-mentioned sixth characteristic, any increase in the size of the engine can be minimized while the air supply capacity of the cooling fan is increased.

Further, according to a seventh aspect of the present invention, in addition to the above-mentioned first aspect, there is proposed a portable four-cycle engine, wherein the timing gear of the valve operating mechanism is constructed as a wrap-around type with a wrapper element, the drive side of the wrapper member extending into the oil tank, wherein an oil mist generating means Producing an oil mist for lubricating the timing transmission by atomizing oil stored within the oil tank in the oil tank; and providing an oil drop guide wall so as to protrude from the inner wall of the oil tank, the oil drop guide wall adhering the oil drops onto the oil tank extending part of the timing gear and drops when the engine is on the side.

According to the above-mentioned seventh characteristic, when the engine is operated in a side-laying state, the oil mist adhered to the oil-drip guide wall results in oil droplets, the droplets then fall on the engaging member to the drive side of the timing transmission, and particularly when the engine is running Upper part of the Umgriffselements moves from the drive side to the output side, the above-mentioned oil droplets can be transported through the Umgriffselement to the output side, with little influence from the centrifugal force occurs, and the output side can be lubricated reliably.

The above Umgriffselement corresponds to the timing belt 25 . 125 . 225 in the embodiments of the present invention described below.

Further, according to an eighth characteristic of the present invention, in addition to the above-mentioned first feature, there is proposed a four-stroke portable engine, wherein the valve operating mechanism is provided above the oil tank disposed outside the engine main body and storing oil, the first valve actuating chamber being arranged such that it extends upwardly from the oil tank, and wherein the second valve actuating chamber is formed in the cylinder head, the oil tank and the crank chamber communicating with each other by means of a through hole, the crank chamber and the second valve actuating chamber communicate with each other by means of an oil supply pipe is provided outside of the engine main body, wherein the second valve actuating chamber and the oil tank communicate with each other by means of an oil return passage, wherein the oil tank, an oil mist generating means for generating a Injecting means by mixing and atomizing the stored oil, namely the pair of slings, and wherein a transfer means for transferring the oil mist within the oil tank to the oil supply pipe via the crank chamber is connected to the oil supply pipe, so that the valve actuating mechanism within the first valve actuating chamber with the inside the oil tank atomized oil is lubricated, and wherein the valve actuating mechanism is lubricated within the second valve actuating chamber with the oil mist transmitted from the oil supply pipe and the second valve actuating chamber.

According to the eighth characteristic of the present invention, because the oil supply pipe is disposed outside the engine main body, it is possible to make the side wall of the engine main body thinner regardless of the presence of the pipe, the engine main body can be made more compact, and the weight of the entire engine can therefore be reduced become. Further, since the oil supply pipe outside the engine main body easily radiates heat, the cooling of the oil mist passing through the pipe can be improved.

Since the lubrication system of the valve operating mechanism is divided into two parts, that is, a part to lubricate the valve operating mechanism within the oil tank and the first valve actuating chamber with the within the Oil tanks sprayed oil, and a system for lubricating the valve actuation mechanism within the second valve actuation chamber with the oil mist directed to the second valve actuation chamber reduces the load applied to each part of the lubrication system and the entire valve actuation mechanism can be reliably lubricated.

Furthermore, regardless of the operating position of the engine, any part of the engine can be reliably lubricated by using oil droplets and oil mist.

Further, according to a ninth characteristic of the present invention, in addition to the eighth characteristic mentioned above, there is proposed a portable four-cycle engine, wherein the transfer means includes a valve means which closes the delivery pipe when the pressure of the crank chamber is a negative pressure, and the pipe opens when the pressure there is an overpressure.

According to the ninth characteristic of the present invention, it is unnecessary to use a special pump for circulating the oil mist, and the structure can be simplified.

Further, according to a tenth property of the present invention, in addition to the above-mentioned eighth or ninth property, there is proposed a portable four-cycle engine wherein the oil supply pipe and the oil return passage are connected to each other via a bypass.

According to the above-mentioned tenth property, the amount of oil mist supplied from the oil supply pipe to the second valve operating chamber can be controlled by appropriately selecting the flow resistance of the bypass.

According to an eleventh aspect of the present invention, in addition to the above-mentioned first feature, there is proposed a portable four-cycle engine, wherein the valve operating mechanism includes the timing gear having a rotary drive member connected to the crankshaft and the cam system for transmitting the rotational force of a rotating output member of the timing transmission to the timing gear Including the intake valve and the exhaust valve for opening and closing forces, wherein the first valve actuating chamber and the oil tank are provided on one side of the engine main body, wherein the first valve actuating chamber, the timing fluid, the oil tank with an oil mist generating means, namely the pair of oil spinners, for generating an oil mist stored oil and the opening inside the oil tank lower end of the first valve actuation chamber, wherein the second valve actuation chamber, the cam system m is provided in the upper part of the engine main body so as to be aligned with the first valve actuating chamber, wherein a first lubrication system includes first and second oil passages arranged side by side to each other and provide communication between the oil tank and the crank chamber, and a first oil supply means for circulating the oil mist generated inside the oil tank from the oil tank via the first oil passage, the crank chamber and the second oil passage back to the oil tank, and wherein a second lubrication system comprises a third oil passage connecting between the first valve actuation chamber and the second valve actuating chamber, includes a fourth oil passage that provides communication between the second valve actuating chamber and the crank chamber, includes the second oil passage, and includes second oil supply means for circulating within the Oil tanks generated oil mist from the oil tank via the first valve actuation chamber, the third oil passage, the second valve actuation chamber, the fourth oil passage, the crank chamber, and the second oil passage back into the oil tank. The rotary drive element and the rotary drive element correspond to the drive pulley 223 and the driven pulley 224 of the third embodiment of the present invention described below, and the oil mist generating means corresponds to the oil slingers 256a and 256b ,

According to the eleventh aspect, because the crankshaft surroundings are lubricated by the first and second lubrication systems, and the timing transmission and the cam system of the valve operating system are lubricated by the second lubrication system, the circumference of the crankshaft which is subjected to a relatively high load can be increased. at the same time it is possible to avoid excessive lubrication of the valve operating mechanism, which is exposed to a relatively small load, the amount of circulating oil mist can be minimized, the amount of stored oil in the oil tank can be reduced and not only Oil tank, but also the whole engine can be made more compact and leichtre.

According to a twelfth feature of the present invention, in addition to the eleventh aspect, there is proposed a portable four-cycle engine, wherein the first oil supply means comprises a first one-way valve provided in the second oil passage and closes when the pressure of the crank chamber is lowered, and that opens when the first one Pressure increases, and wherein the second oil supply means comprises a second one-way valve provided in the third oil passage closes when the pressure the crank chamber drops and this opens when the pressure rises.

According to the twelfth characteristic, the oil mist inside the oil tank can be transmitted by using the pressure pulses inside the crank chamber and the one-way transmission functions of the first and second one-way valves, therefore, it is not necessary to use a special oil pump for circulating the oil mist and therefore the structure can be simplified become.

The above objects and other objects, features and advantages of the present invention will become clear from an explanation of preferred embodiments which will be described below in detail with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

1 to 11 show a non-inventive embodiment, which is provided to facilitate the understanding of the invention.

1 Fig. 11 is an oblique view showing an embodiment of a portable four-cycle engine in practical use.

2 is a longitudinal side view of the above four-stroke engine.

3 is an enlarged view of an important part of 2 ,

4 is an enlarged vertical sectional view around the crankshaft in 3 ,

5 is a cross-sectional view along 5-5 in 3 ,

6 is a schematic view of the lubrication system of the above-mentioned engine.

7 is a cross-sectional view along 7-7 in 3 ,

8th is a cross-sectional view taken along 8-8 in FIG 7 ,

9 is a bottom view of the head cover.

10 is an explanatory view of the effect of the suction of the cylinder head located oil in different operating positions of the engine.

11 is a cross-sectional view accordingly 7 showing a modified embodiment of the oil supply pipe and the oil return pipe.

12 to 24 show a first embodiment of the present invention.

12 Fig. 12 is a longitudinal side view of the four-stroke portable engine of the present invention.

13 is a cross-sectional view along 13-13 in FIG 12 ,

14 is a cross-sectional view taken along 14-14 in FIG 12 ,

15 is an enlarged cross-sectional view of an important part of 12 ,

16 is an exploded view of an important part of 15 ,

17 is a cross-sectional view along 17-17 in FIG 14 ,

18 is a cross-sectional view along 18-18 in 14 ,

19 is a cross-sectional view along 19-19 in 18 ,

20 is a cross-sectional view along 20-20 in 15 (View of the head cover from below).

21 is a cross-sectional view along 21-21 in 15 ,

22 is a diagram showing the lubrication path of the above-mentioned engine.

23 is a view accordingly 14 in which the above-mentioned engine is in an inverted state.

24 is a view accordingly 14 in which the above-mentioned engine is in an off-side condition.

25 to 36 show a second embodiment of the present invention.

25 Fig. 12 is a longitudinal side view of the four-stroke portable engine of the present invention.

26 is a cross-sectional view along 26-26 in 25 ,

27 is a cross-sectional view along 27-27 in FIG 25 ,

28 is an enlarged cross-sectional view of an important part of 25 ,

29 is an exploded view of an important part of 28 ,

30 is a cross-sectional view along 30-30 in 27 ,

31 is a cross-sectional view along 31-31 in FIG 27 ,

32 is a cross-sectional view taken along 32-32 in FIG 28 (View of the head cover from below).

33 is a cross-sectional view along 33-33 in FIG 28 ,

34 is a diagram showing the lubrication path of the above-mentioned engine.

35 is a view accordingly 27 in which the above-mentioned engine is in an inverted state.

36 is a view accordingly 27 in which the above motor is in an off-side condition.

DESCRIPTION OF PREFERRED EMBODIMENTS

First, in the following, the in 1 to 11 not shown embodiment described.

As in 1 is shown, a portable four-stroke engine E is formed as a power source for the driving portion of, for example, a motor-driven trimmer T. As a result, since the motor-driven trimmer T is used in a manner in which a cutting device C is arranged in different directions according to the operating conditions, the motor E is also largely tilted or reversed and the operating position is not stable.

First, the overall construction of the four-stroke portable engine will be described with reference to FIG 2 to 5 explained.

As in 2 . 3 and 5 shown are a carburetor 2 and a muffler 3 respectively at the front and the rear of the engine main body 1 of the above-mentioned four-stroke portable engine E, and an air cleaner 4 is at the inlet of the carburetor 2 appropriate. A fuel tank made of a synthetic resin 5 is on the lower surface of the engine main body 1 appropriate.

The engine main body 1 includes a crankcase 6 with a crank chamber 6a , a cylinder block 7 with a cylinder bore 7a as well as a cylinder head 8th with a combustion chamber 8a and intake and exhaust ports 9 and 10 entering the combustion chamber 8a lead. The cylinder block 7 and the cylinder head 8th are integrally cast and the separately cast crankcase 6 is by bolts with the lower end of the cylinder block 7 connected. The crankcase 6 is from a first in a second housing half 6L and 6R formed, and the two housing halves 6L and 6R are together by means of a bolt 12 in the middle of the crankcase 6 connected. A large number of cooling fins 38 is at the outer peripheries of the cylinder block 7 and the cylinder head 8th educated.

One in the crank chamber 6a housed crankshaft 13 is rotatable in the first and the second half of the housing 6L and 6R over ball bearings 14 and 14 ' stored and is with a piston 15 in the cylinder bore 7a over a connecting rod 16 attached, connected. Furthermore, there are oil seals 17 and 17 ' in the first and the second half of the housing 6L and 6R used, with the oil seals 17 and 17 ' to the above bearings 14 and 14 ' abut and in close contact with the outer circumference of the crankshaft 13 are located.

An inlet valve 18 and an exhaust valve 19 for opening and closing respectively the inlet opening 9 and the outlet opening 10 are in the cylinder head 8th parallel to the axis of the cylinder bore 7a provided and a spark plug 20 is screwed in such that its electrodes are close to the central region of the combustion chamber 8a are located.

The inlet valve 18 and the exhaust valve 19 are forcibly closed by means of valve springs 22 and 23 in a valve cam actuating chamber 21 in the cylinder head 8th is trained. In the valve cam actuation chamber 21 are cam followers 24 and 25 in the cylinder head 8th are stored in a vertically tiltable manner, on the top of the inlet valve 18 and the exhaust valve 19 hung up, and a camshaft 26 for opening and closing the inlet valve 18 and the exhaust valve 19 over the cam followers 24 and 25 is rotatable by ball bearings 27 ' and 27 in the right and left side walls of the valve cam actuating chamber 21 stored, with the camshaft 26 parallel to the crankshaft 13 runs. A side wall of the valve cam actuating chamber 21 in which the camp 27 is attached, is integral with the cylinder head 8th trained, and an oil seal 28 is in this side wall in close contact with the outer circumference of the camshaft 26 appropriate. The other side wall of the valve cam actuating chamber 21 is with an insertion hole 29 provided to allow the camshaft 26 in the Valve cam operation chamber 21 is used, and after inserting the camshaft 26 becomes the other camp 27 ' in a sidewall cover 30 attached, the insertion opening 29 blocked. The side wall cover 30 is in the insertion hole 29 via a sealing element 31 used and with the cylinder head 8th connected by a bolt.

As in 3 and 4 can clearly be seen, is an end of the camshaft 26 from the cylinder head 8th on the side of the above oil seal 28 in front. One end of the crankshaft 13 also stands from the crankcase 6 on the same side, a toothed drive pulley 32 is at this end of the crankshaft 13 attached, and a toothed driven pulley 33 which has twice as many teeth as the drive pulley 32 , is at the end of the above camshaft 26 attached. A toothed timing belt 34 is around the two pulleys 32 and 33 wrapped so that the crankshaft 13 the camshaft 26 with a reduction ratio of 1: 2 can drive. The above camshaft 26 and a timing transmission 35 form a valve actuating mechanism 53 ,

The engine E is therefore arranged in the form of an OHC type and the timing transmission 35 is arranged in the form of a dry type, which is arranged outside of the engine main body.

A belt cover made of synthetic resin 36 is between the engine main body and the timing transmission 35 arranged, with the belt cover 36 on the engine main body 1 by means of a bolt 37 is fixed so as to prevent that from the engine main body 1 radiated heat the timing gearbox 35 impaired.

An oil tank made of synthetic resin 40 is arranged such that it forms part of the outer surface of the timing gear 35 covers and is on the engine main body 1 by means of a bolt 41 attached and continues to be a starter 42 of the rewind type (see 2 ) on the outer surface of the oil tank 40 attached.

Referring again to 2 is the end of the crankshaft 13 indicating the end of the timing transmission 35 is opposite, also from the crankcase 6 in front, and a flywheel 43 is at this end by means of a mother 44 attached. A large number of cooling blades 45 . 45 ... are integral with the inner surface of the flywheel 43 provided such that the flywheel 43 can also act as a coolant. A plurality of fastening approaches 46 (one of them is in 2 shown) is on the outer surface of the flywheel 43 trained and a centrifugal shoe 47 is pivotable on each of the attachment lugs 46 stored. These centrifugal shoes 47 form together with a clutch drum 48 attached to a drive shaft 50 , which is described below, is attached, a centrifugal clutch 49 , and if the rotational speed of the crankshaft 13 exceeds a predetermined value, the centrifugal shoes 47 due to the centrifugal force of the shoes on the inner circumference of the clutch drum 48 pressed to the output torque of the crankshaft 13 to the drive shaft 50 transferred to. The flywheel 43 has a larger diameter than that of the centrifugal clutch 49 ,

An engine cover 51 that the engine main body 1 and its accessories is at the location of the timing gearbox 35 in a first cover half 51a on the side of the flywheel 43 and a second cover half 51b on the side of the starter 52 divided, and each of the cover halves 51a and 51b is on the engine main body 1 attached. A bearing holder formed in the shape of a truncated cone 58 , which is coaxial with the crankshaft 13 is disposed on the first cover half 51a attached, the storekeeper 58 the drive shaft 50 stores, which the above-mentioned cutting device C via a pivot bearing 59 turns, and an air intake opening 52 is in the storekeeper 58 provided so that outside air by rotation of the cooling blades 45 . 45 ... is sucked into the interior of the engine cover. Further, a base 54 for covering the lower surface of the fuel tank 5 on the engine cover 51 and the storekeeper 58 attached.

Because the timing gearbox 35 for operational connection of the crankshaft 13 with the camshaft 26 as a dry type outside of the engine main body 1 is constructed, it is, as mentioned above, not necessary, a special space for receiving the transmission 35 on the side wall of the engine main body 1 to provide, and it is therefore possible, the engine main body 1 thin and compact and to reduce the total weight of each engine E to a great extent.

Since the timing transmission continues 35 and the centrifugal shoes 47 the centrifugal clutch 49 with the two ends of the crankshaft 13 are connected, wherein the cylinder block 7 arranged between them are the weights of the two ends of the crankshaft 13 Well balanced, the center of gravity of the engine E can be as close as possible to the middle part of the crankshaft 13 can be selected and the handling of the engine E can therefore be increased, while the weight can be reduced. Furthermore, since the burdens of the Timing gear 35 and the drive shaft 50 separated on the two ends of the crankshaft 13 During the operation of the engine E, it is possible to prevent the load on the crankshaft 13 and the camp 14 . 14 ' which the crankshaft 13 store, is localized and their durability can therefore be improved.

Further, as the flywheel 43 which has a larger diameter than that of the centrifugal clutch 49 and the cooling blades 45 has, on the crankshaft 13 between the engine main body 1 and the centrifugal clutch 49 attached, outside air can effectively around the cylinder block 7 and the cylinder head 8th be supplied around by the air through the air intake 52 by turning the cooling blades 45 without interference from the centrifugal clutch 49 is introduced, which improves the cooling characteristics, while any increase in the size of the engine E due to the flywheel 43 is avoided.

Because the oil tank continues 40 on the engine main body 1 is fixed so that it is on the outside of the timing gear 35 adjoins, the oil tank covers 40 at least part of the timing transmission 35 and can the transmission 35 in cooperation with the second cover half 51b that the other part of the transmission 35 covers, protect. Because the oil tank continues 40 and the flywheel 43 are arranged so that they face each other, wherein the engine main body 1 placed between them, the center of gravity of the engine E can be closer to the middle part of the crankshaft 13 be placed.

The lubrication system of the above-mentioned engine E will be described below with reference to FIG 3 to 10 explained.

As in 3 is shown, the crankshaft is arranged such that one end thereof through the oil tank 40 runs while keeping in close contact with the oil seals 39 and 39 ' located on both the outer and inner walls of the oil tank 40 are attached, and a through hole 55 which connects the interior of the oil tank 40 and the crank chamber 6a is in the crankshaft 13 intended. Lubricating oil O is in the oil tank 40 is stored and the stored amount is set such that an open end of the above-mentioned through-hole 55 inside the oil tank 40 is always above the liquid level of the oil O, regardless of the operating position of the engine E.

An oil spinner 56 is on the crankshaft 13 inside the oil tank 40 by means of a mother 57 attached. The oil spinner 56 includes two blades 56a and 56b which are in radially opposite directions from the central part at which the oil spinner 56 on the crankshaft 13 is attached, run and which are bent axially opposite to each other in directions. If the oil spinner 56 through the crankshaft 13 is rotated, sprayed at least one of the two blades 56a and 56b the oil inside the oil tank 40 to generate an oil mist regardless of the operating position of the engine E.

As in 3 . 6 and 7 is shown is the crank chamber 6a with the valve actuation chamber 21 via an oil supply pipe 60 connected and a one-way valve 61 is in the oil supply pipe 60 provided to only a flow in the direction of the crank chamber 6a to the valve cam actuating chamber 21 to allow. The oil supply pipe 60 is integral with the above belt cover 36 formed along one of its side edges and the lower end of the Ölzuführrohrs 60 is in a valve chamber 62 educated. An inlet pipe 63 which is from the valve chamber 62 behind the belt cover 36 protrudes, is integral with the belt cover 36 formed, and the inlet pipe 63 is in a connection hole 64 in the lower part of the crankcase 6 via a sealing element 65 inserted, leaving the inlet pipe 63 communicating with it to connect to the crank chamber 6a provide. The aforementioned one-way valve 61 is inside the valve chamber 62 provided to a flow in the direction of the inlet pipe 63 to the valve chamber 62 to enable. In the case of the embodiment shown, this one-way valve 61 a tongue valve.

An outlet pipe 66 , which from the upper end of the Ölzuführrohrs 60 at the back of the belt cover 36 protrudes, is integral with the belt cover 36 formed, and the outlet pipe 66 is in a connection hole 67 on one side of the cylinder head 8th inserted, leaving the inlet pipe 66 with the valve cam actuating chamber 21 communicates.

The way with the oil supply pipe 60 related valve cam actuation chamber 21 stands with a breather chamber 69 inside the side wall cover 30 via a gas / liquid separation passage 68 in connection, in the camshaft 26 is provided and a transverse hole 68a and a longitudinal hole 68b and the breather chamber 69 stands with the interior of said air cleaner 4 via a vent pipe 70 in connection.

As in 4 and 9 clearly shown is a head cover 71 for blocking the open upper surface of the valve cam actuating chamber 21 with the cylinder head 8th via a sealing element 72 connected. A suction chamber 74 that with the Valve cam operation chamber 21 over a plurality of openings 73 . 73 ... is in the head cover 71 educated. The suction chamber 74 has a flattened shape along the upper surface of the valve cam actuating chamber 21 and is with four openings 73 . 73 ... provided at four points in its bottom wall. One long and one short suction tube 75 and 76 are integral with the bottom wall of the suction chamber 74 formed in its central area, with a space between the long and the short suction tube 75 and 76 in the direction perpendicular to the axis of the camshaft 26 is present, allowing it into the valve cam actuation chamber 21 protrude, and openings 73 and 73 are in the suction pipes 75 and 76 intended.

As in 6 to 8th is shown, the suction chamber is 74 also with the interior of the oil tank 40 via an oil return pipe 78 in connection. The oil return pipe 78 is integral with the belt cover 36 formed along the edges thereof on the side, that of the Ölzuführrohrs 60 opposite. An inlet pipe 79 , which from the upper end of the oil return pipe 78 at the back of the belt cover 36 protrudes, is integral with the belt cover 36 trained and the inlet pipe 79 is over a connector 81 with an outlet pipe 80 in connection, which in the head cover 71 is formed, so that the inlet pipe 79 with the suction chamber 74 communicates.

Furthermore, an outlet pipe 82 from the lower end of the oil return tube 78 at the back of the belt cover 36 protrudes, integral with the belt cover 36 formed, and the outlet pipe 82 is in a return pipe 83 used, which in the oil tank 40 is provided, so that the outlet pipe 82 with the interior of the oil tank 40 communicates. The open end of the return hole 83 is near the central part of the oil tank 40 arranged so that the open end is above the liquid level of the oil inside the oil tank 40 regardless of the operating position of the engine E.

An output element 84 which by the above starter 42 is driven by the rewind type, is at the front end of the crankshaft 13 attached, which from the oil tank 40 protrudes.

Through the oil spinner 56 which lubricating oil O within the oil tank 40 due to the rotation of the crankshaft 13 splashed during operation of the engine E, oil mist is generated, and when the pressure of the crank chamber 23 due to the increasing movement of the piston 15 goes back, the thus generated oil mist over the through hole 55 in the crank chamber 6a sucked in this way the crankshaft 13 and the piston 15 to lubricate. When the pressure of the crank chamber 6a due to the descent of the piston 15 rises, the one-way valve opens 61 and as a result, the above-mentioned oil mist inside the oil supply pipe increases 60 together with the in the crank chamber 6a generates blowby gas and becomes the valve cam actuating chamber 21 fed to the camshaft in this way 26 , the cam followers 24 and 25 etc. to lubricate.

When the oil mist and the blow-by gas inside the valve cam actuating chamber 21 the gas / liquid separation passage 68 inside the rotating crankshaft 26 enter gas and liquid by centrifugal forces within the passage 68 disconnected, the liquefied oil becomes the valve cam actuating chamber 21 over the transversal hole 68a the gas / liquid separation passage 68 returned, but the blowby gas is in the engine E via the breather chamber 69 , the breather pipe 70 and the air purifier 4 sucked in this order during the intake stroke of the engine E.

Since the valve cam actuation chamber 21 with the interior of the air purifier 4 as mentioned above via the gas-liquid separation passage 68 , the breather chamber 69 and the breather pipe 70 communicates, the pressure within the valve cam actuating chamber 21 held at the same or slightly lower level than the ambient pressure.

On the other hand, the pressure in the crank chamber 6a on average, a negative pressure, since the overpressure component of the pressure pulses solely by the one-way valve 61 is ejected. The negative pressure becomes an oil tank 40 over the through hole 55 and further to the suction chamber 74 over the oil return pipe 78 transfer. The pressure in the suction chamber 74 is therefore lower than that of the valve cam actuating chamber 21 and the pressure inside the oil tank 40 is lower than that in the suction chamber 74 , As a result, the pressure from the valve cam actuating chamber becomes 21 to the suction chamber 74 over the suction pipes 74 and 76 and the openings 73 . 73 ... and on to the oil tank 40 over the oil return pipe 78 be transferred and accompanying to this transfer, the within the Ventilnockenbetätigungskammer 21 generated oil mist and in the Ventilnockenbetätigungskammer 21 retained liquefied oil through the suction pipes 74 and 76 and the openings 73 . 73 ... up into the suction chamber 74 sucked and through the oil return pipe 78 in the oil tank 40 recycled.

Since, as mentioned above, the four openings 73 . 73 ... at four points of the bottom wall of the suction chamber 74 are provided and the openings 73 and 73 in the long and short suction tube 74 and 75 in the Valve cam operation chamber 21 projecting from the middle part of the bottom wall, with a space between the long and the short suction pipe 74 and 75 in the directions perpendicular to the axis of the camshaft 26 is provided regardless of the operating position of the engine E, such as an upright state (A), a left-leaning state (B), a right-leaning state (C), a left-leaning state (D), a to the right (E), or an inverted (F), as in 10 shown is one of the six openings 73 . 73 ... in the valve cam actuating chamber 21 stored oil submerged and the oil can enter the suction chamber 74 be sucked.

Because that way in the oil tank 40 generated oil mist in this way the crank chamber 6a and the valve cam actuating chamber 21 the four-stroke engine E OHC type using the pressure pulses within the crank chamber 6a and the function of the one-way valve 61 is fed and to the oil tank 40 is returned, the interior of the engine E can be reliably lubricated by the oil mist, regardless of the operating position of the engine E; Further, a special oil pump for circulating the oil mist is not necessary, and the structure can therefore be simplified.

Not just the oil tank 40 made of synthetic resin, but also the oil supply pipe 60 which connects between the crank chamber 6a and the valve cam actuating chamber 21 and the oil return tube 78 which connects the suction chamber 74 and the oil tank 40 are outside the engine main body 1 There is no obstacle in forming the engine main body 1 thinner and more compact, and this can greatly contribute to a reduction in the weight of the engine E. In particular, the externally arranged Ölzuführrohr 60 and oil return pipe 78 less by heat from the engine main body 1 are influenced, overheating of the lubricating oil O can be prevented. Furthermore, the integral formation of the oil supply pipe 60 , the oil return pipe 78 and the belt cover 36 contribute to a reduction in the number of parts and an improvement in assembly properties.

11 shows a modified embodiment of the Ölzuführrohrs 60 and the oil return tube 78 and in this case are the oil supply pipe 60 and the oil return pipe 78 formed from a tube made of a flexible material, such as rubber, and those of the belt cover 36 is disconnected. Since the other components are the same as those in the above embodiment, the same reference numerals are given in corresponding parts in the drawings and their explanation is omitted.

According to the modified embodiment, the oil supply pipe 60 and the oil return pipe 78 be attached freely to the connection of points, wherever the points are arranged by the tubes 60 and 48 be bent suitably, and the degree of freedom of the design can be increased.

It is also possible in the above-mentioned first embodiment, that a rotary valve, which in operation with the crankshaft 13 is connected and to release the Ölzuführrohrs 60 serves when the piston 15 moves down and to block the oil supply pipe 60 serves when the piston 15 moves up instead of the one-way valve 61 is provided.

Hereinafter, a first embodiment of the present invention will be described with reference to FIG 12 to 24 explained.

As in 12 and 13 shown are a carburetor 102 and a muffler 103 respectively at the front and rear of a motor main body 101 a portable four-stroke engine E attached, and an air cleaner 104 is at the inlet of the carburetor 102 appropriate. A fuel tank made of a synthetic resin 105 is on the lower surface of the engine main body 101 appropriate. The two ends of a crankshaft 113 stand by the engine main body 101 and an oil tank 140 that is to a side of the engine main body 101 is adjacent, forth and a starter 142 of the rewinding type, which in transferring manner with an output element 184 , which is at one end of the crankshaft 113 attached, is connected to the outer surface of the oil tank 140 appropriate.

A cooling fan 143 , which also serves as a flywheel, is at the other end of the crankshaft 113 attached. A plurality of fastening approaches 146 (one of which is in 12 is shown) is on the outer surface of the cooling fan 143 trained, and a centrifugal shoe 147 is pivotable on each of these mounting lugs 146 stored. These centrifugal shoes 147 form together with a clutch drum 148 attached to a drive shaft 150 , which is described below, is attached, a centrifugal clutch 149 , and if the rotational speed of the crankshaft 113 exceeds a predetermined value, the centrifugal shoes 147 on the inner circumference of the clutch drum 148 due to the centrifugal force of the shoes pressed to the output torque of the crankshaft 113 to the drive shaft 150 transferred to. The cooling fan 143 has a larger diameter than that of the centrifugal clutch 149 ,

An engine cover 151 that the engine main body 101 and its accessories with Exception of the fuel tank 140 is at appropriate positions of the engine main body 101 attached, and a cooling air inlet 119 is between the engine cover 151 and the fuel tank 105 intended. Outside air is therefore through the cooling air inlet 119 through the rotating cooling fan 143 sucked and fed to the cooling of each part of the engine E.

A bearing holder formed in the shape of a truncated cone 158 , which is coaxial with the crankshaft 113 is located on the engine cover 151 attached, and the storage holder 158 stores the drive shaft 150 which the cutting device C of the trimmer T (see 1 ) about a camp 159 in the same manner as in the above-mentioned first embodiment.

Because the oil tank 150 and the starter 152 on one side and the cooling fan 143 and the centrifugal clutch 149 are arranged on the other side, wherein the engine main body 101 between them, the weight distribution of the engine E between the right and left directions can be improved, and the center of gravity of the engine E can be closer to the central part of the engine main body 101 be placed so that the handling of the engine E is improved.

Further, because the cooling fan 143 having a larger diameter than that of the centrifugal shoes 147 , on the crankshaft 113 between the engine main body 101 and the centrifugal clutch 149 fixed, it is possible to any increase in the dimensions of the engine E due to the cooling fan 141 to avoid.

The structure of the engine main body 101 and the oil tank 140 are below with reference to 12 to 15 . 16 . 20 and 21 explained.

In 12 to 15 includes the engine main body 101 a crankcase 106 with a crank chamber 106a , a cylinder block 107 with a cylinder bore 107a , a cylinder head 108 with a combustion chamber 108a and inlet and outlet openings 109 and 110 entering the combustion chamber 108a and a large number of cooling fins 138 on the outer perimeters of the cylinder block 107 and the cylinder head 108 are formed.

The in the crank chamber 106a housed crankshaft 113 is on the left and right sides of the crankcase 106 over ball bearings 114 and 114 ' stored. In this case, the left ball bearing 114 equipped with a gasket, and an oil seal 117 is provided so that it is the outside of the right ball bearing 114 ' is adjacent. A piston 115 in the cylinder bore 107a is used, is in a conventional manner with the crankshaft 113 over a connecting rod 116 connected in a common way.

The oil tank 140 is provided so as to be integral with the left wall of the crankcase 106 is formed, and is arranged such that the end of the crankshaft 113 on the side of the sealed ball bearing 114 through the oil tank 140 runs. An oil seal 139 through which the crankcase 113 runs, is in the outer wall of the oil tank 140 attached.

A belt guide tube 186 with flattened cross-section is integral with the roof of the oil tank 140 provided, wherein the belt guide tube 186 vertically through the roof of the oil tank 140 runs and has an open upper and a lower end. The lower end of the oil guide tube 186 runs close to the crankshaft 113 inside the oil tank 140 and the upper end is integral with the cylinder head 108 provided so that it is a separator 185 with the cylinder head 108 Splits. A line of a circular sealing bead 187 is around the circumference of the upper end of the belt guide tube 186 around the cylinder head 108 formed, and the separating element 185 stands over the sealing bead 187 in front.

As in 16 . 20 and 21 is shown, is one of the above-mentioned sealing bead 187 corresponding circular sealing groove 188a in the lower end surface of a cylinder head cover 136 formed, and a linear sealing groove 188b which are the two sides of the circular groove 188a Connecting with each other is with the inner surface of the cover 136 educated. A circular pack 189a is in the circular sealing groove 188a used, and a linear packing 189b that is integral with the circular packing 189a is formed is in the linear sealing groove 188b used. The head cover 136 is with the cylinder head 108 by means of a bolt 137 connected so that the sealing bead 187 and the separator 185 each in contact with the circular packing 189a and the linear pack 189b be pressed.

The belt guide tube 186 and one half of the head cover 136 form a first valve actuation chamber 121 , the cylinder head 108 and the other half of the head cover 136 form a second valve actuation chamber 121b and the two valve actuation chambers 121 and 121b are through the above separator 185 separated.

Referring again to 12 to 15 are the engine main body 101 and the oil tank 140 divided into the upper block Ba and a lower block Bb at a plane which is the axis of the crankshaft 113 contains and orthogonal to Axle of the cylinder bore 107a is. That is, the upper block Ba integrally includes the upper half of the crankcase 106 , the cylinder block 107 , the cylinder head 108 , the upper half of the oil tank 140 and the belt guide tube 186 , The lower block Bb integrally includes the lower half of the crankcase 106 and the lower half of the oil tank 140 , These upper and lower blocks Ba and Bb are individually molded and connected to each other by a plurality of bolts 112 (please refer 14 ) after each part has been manufactured.

An inlet valve 118i and an exhaust valve 118e for opening and closing respectively the inlet opening 109 and the outlet opening 110 are in the cylinder head 108 provided such that they are parallel to the axis of the cylinder bore 107a are, and a spark plug 120 is screwed in such that its electrodes are in the vicinity of the central region of the combustion chamber 108a are located.

A valve actuating mechanism 122 for opening and closing the above intake valve 118i and exhaust valve 118e is below with reference to 13 to 17 explained.

The valve actuating mechanism 122 contains a timing gearbox 122a of the Umgriffstyp, which from the inside of the oil tank 140 to the first valve actuating chamber 121 runs, and a cam system 122b which is from the first valve actuation chamber 121 to a second valve actuating chamber 121b runs.

The timing transmission 122a The wrapper type includes a drive pulley 123a , on the crankshaft 113 inside the oil tank 140 attached, an output pulley 124 pivotally mounted in the upper part of the belt guide tube 186 is stored, and a timing belt 125 , that around this drive pulley and driven pulley 123 and 124 is wound. On the side of the separator 125 is the end face of the driven pulley 124 integral with a cam 126 connected, which is part of the cam system 122b forms. The drive pulley and driven pulley 123 and 124 are provided with teeth and the drive pulley 123 drives the driven pulley 124 over the belt 125 with a reduction ratio of 1: 2.

A warehouse wall 127 is integral with the outer wall of the belt guide tube 186 formed, with the bearing wall 127 within the circular sealing bead 187 rises and in contact or near the inner surface of the head cover 136 located. A through hole 128 and a bottomed blind hole 128b , which coaxially above the sealing bead 187 are provided, each in the storage wall 127 and the separator 185 intended. Both ends of a carrier wave 129 are rotatable through the through hole 128a and the bottomed blind hole 128b stored, and the above driven pulley 136 and the cam 126 are rotatable on the middle part of the bearing shaft 129 stored. Before the head cover 136 is attached, the bearing shaft 129 from the through hole 128a in a shaft hole 135 the driven pulley 124 and the cam 126 and in the bottomed blind hole 126b introduced. After insertion, the head cover 136 with the cylinder head 108 and the belt guide hole 186 connected so that the inner surface of the head cover 136 towards the outer end of the carrier shaft 129 thus acting as a stop to prevent the shaft 129 out of the hole 128a falls out, and the bottom of the bottomed blind hole 128b limits movement of the shaft 129 inside. The bearing shaft 129 is therefore limited in its movement inwardly and outwardly in the axial direction.

It is therefore unnecessary, a special stop element for the bearing shaft 129 to provide the bearing shaft 129 can inside the head cover 136 be provided, leakage of oil can be through an oil-tight connection between the head cover 136 and the cylinder head 108 be prevented and it is therefore not necessary, a special sealing element on the bearing shaft 129 so as to reduce the number of parts and the cost. Furthermore, in the storage wall 127 that are inside the sealing bead 187 rises, the through hole 128a arranged at a higher position than that of the sealing bead 187 , the head cover 136 is formed such that the inner surface of the head cover 136 in contact with or near the outer surface of the bearing wall 127 located and the head cover 136 Therefore, it can be made more compact while allowing the bearing shaft 129 is removable before the head cover 136 is removed.

A pair of bearing approaches 130i and 130e parallel to the bearing shaft 129 project, are integral with the separator 185 on the side of the second valve actuating chamber 121b educated. The cam system 122b includes the above cam 126 , an intake rocker arm shaft 131i and an exhaust rocker arm shaft 131e , each rotatable in the above bearing approaches 130i and 130e are stored, an intake cam follower 132i and an exhaust cam follower 132e , each at one end of the rocker shafts 133i and 133e within the first valve actuation chamber 121 are attached, wherein the front end of each of the intake cam followers 132i and exhaust cam follower 132e yourself in sliding contact with the lower surface of the cam 126 with an intake rocker arm 133i and an exhaust rocker arm 133e each at the other end of the intake and Auslasskipphebelwelle 133i and 133e within the second valve actuation chamber 121b are attached, wherein the front end of each of the intake rocker arms 133i and exhaust rocker arms 133e in contact with the upper end of both the inlet valve 118i as well as the exhaust valve 118e is located, and wherein an inlet spring 134i and an exhaust spring 134e each at the inlet valve 118i and the exhaust valve 118e are attached and apply the same in the closing direction.

When the crankshaft 113 turns, turns the drive pulley 123 , which work together with the crankshaft 113 turns, the driven pulley 124 and the cam 126 over the belt 125 , the cam 126 then moves the inlet and exhaust cam followers 132i and 132e with a suitable timing, the tilting movements are on the intake and Auslasskipphebelarme 133i and 133e via corresponding rocker arm shafts 131i and 131e and the tilted intake and exhaust rocker arms in this manner 133i and 133e can the intake and exhaust valves 118i and 118e with an appropriate timing open and close while using the inlet and outlet springs 134i and 134e work together.

Because in the timing transmission 122a the driven pulley 124 and the cam 126 rotatable by the bearing shaft 129 are stored and the bearing shaft 129 moreover rotatable in both side walls of the first valve actuating chamber 121 is stored, the bearing shaft rotates 129 due to frictional resistance during rotation of the driven pulley 124 and the cam 126 where the difference in speed between the bearing shaft 129 and the driven pulley 124 and the cam 126 can be reduced and wear of the rotating and sliding areas can be suppressed. The life of the cam 126 and the bearing shaft 129 can therefore be improved without any special material or surface treatment.

The cam 126 which has a comparatively large diameter is on one side of the cylinder head 108 together with the driven pulley 124 arranged, and only the inlet and Auslasskipphebelarme 133i and 133e and the intake and exhaust rocker shafts 131i and 131e which have a comparatively small diameter are immediately above the cylinder head 108 arranged. The valve actuating mechanism 122 therefore does not require a large space above the cylinder head 108 and it is possible to reduce the overall height of the engine E, whereby the engine E can be made more compact.

Further, since the bearing shaft 129 and the intake and exhaust rocker shafts 131i and 131e are arranged at a higher position than that of the line of the circular sealing bead 187 at the top of the cylinder head 108 and the belt guide tube 186 , it is therefore possible the bearing shaft 129 and the intake and exhaust rocker shaft 131i and 131e above the sealing bead 187 without disability of the same in a state in which the head cover 136 is removed, assemble and disassemble, and an exceptionally easy installation and maintainability is achieved.

The lubrication system of the above-mentioned engine E will be described below with reference to FIG 13 to 22 explained.

As in 14 and 15 shown, the oil tank stores 140 a predetermined amount of lubricating oil O passing through an oil inlet 140 is filled. Inside the oil tank 140 are a pair of slingshots 156a and 156b on each side of the drive pulley 123 in the axial direction in a press fit, etc. on the crankshaft 113 attached. These slingshots 156a and 156b extend in directions radially opposite to each other and their front ends are bent so that they move away from each other in the axial direction, so that when the oil spinner 156a and 156b through the crankshaft 113 be turned, at least one of the slingshots 156a and 156b that within the oil tank 140 Stored oil is stirred and sprayed to produce regardless of the operating position of the engine E an oil mist. In this case, the oil mist is over part of the timing gear 122a sprayed, which in the oil tank 140 from the first valve actuating chamber 121 out, or the oil mist reaches the first valve actuation chamber 121 and the timing transmission 122 can therefore be lubricated directly, and this provides a lubrication system.

Another lubrication system includes, as in 13 to 15 and 22 shown is one in the crankshaft 113 provided through hole 125 to make a connection between the interior of the oil tank 140 and the crank chamber 106a to provide an oil feed tube 160 which is outside of the engine main body 101 is provided to the lower part of the crank chamber 106a with the lower part of the second valve actuating chamber 121b to connect, an oil collection chamber 174 , which in the cylinder head 108 is provided to liquefied oil, which in the second valve actuation chamber 121b remains to collect, an oil return passage 178 that is between the cylinder head 108 and the oil tank 140 is trained to connect between the oil collection chamber 174 and the oil tank 140 via the first valve actuation chamber 121 to provide, as well as a one-way valve 161 , which is in the lower part of the crank chamber 106a is provided and allows the oil mist only in the direction of the crank chamber 106a to the oil supply pipe 160 flows.

An open end 155a of the above-mentioned through hole 155 inside the oil tank 140 is in the middle part or near the same inside the tank 140 arranged so that the open end 155a regardless of the operating position of the engine E is always above the liquid level of the oil O within the oil tank. The drive pulley 123 and one of the oil spinners 156a are at the crankshaft 113 attached, with the open end 155a interposed, to the open end 155a not to block.

The above-mentioned one-way valve 161 (please refer 13 ), which in the embodiment shown comprises a reed valve, closes when the pressure of the crank chamber 106a with the reciprocation of the piston 115 concomitantly becomes a negative pressure, and opens when the pressure becomes an overpressure.

The lower end of the oil supply pipe is connected by fixing it on a lower connecting pipe 162a , which is provided such that it is out of the outer surface of the crankcase 106 protrudes (see 13 ), and the upper end of the oil supply pipe 160 is connected by connecting it to an upper connecting pipe 182b is fixed, which is provided such that it from the outer surface of the cylinder head 108 protrudes (see 14 and 18 ). The interior of the upper connecting pipe 182b is at the lower part of the second valve actuating chamber 121b on one side via a connection passage 163 (please refer 18 and 19 ), which in the cylinder head 108 is formed and has large dimensions, and is with the oil return passage 178 on the other side via a bypass 164 associated with openings (see 18 ).

As in 15 . 20 and 21 is shown is a separation plate 165 which a breather chamber 169 in the upper part of the head cover 136 defined on the ceiling of the cover 136 by means of a plurality of support struts 166 and on the struts 166 attached ironing 167 fastened, with the support struts 166 are provided so that they protrude from the ceiling. The breather chamber 169 communicates with the second valve actuating chamber 121b on one side via a feed tube 168 and a gap g between the inner surface of the head cover 136 and the separator plate 165 in conjunction with the connecting pipe 168 , which has large dimensions, integral with the partition plate 165 is formed and to the second valve actuating chamber 121b protrudes. The breather chamber 169 moreover, stands with the interior of the above-mentioned air purifier 104 on the other side via a breather pipe 170 in connection. In the breather chamber 169 a mixture of oil and blowby gas is separated into gas and liquid, and a labyrinth wall 172 for promoting the gas / liquid separation is provided such that it from the inner surface of the ceiling of the head cover 136 protrudes.

To the partition plate 165 is a box-shaped separator 179 welded, which from the view from above has an open surface and a T-shape, wherein the box-shaped separating element 179 the above-mentioned oil catchment chamber 174 in the room on the upper surface of the partition plate 165 forms, and wherein the oil collection chamber 174 therefore also T-shaped.

Two suction pipes 175 are integral with the separator plate 165 formed so as to project from the same, wherein the two suction pipes 175 each with the two ends of the lateral spar of the T-shaped oil collecting chamber 174 keep in touch. The front end of each of the suction pipes 175 runs in the direction of the vicinity of the base of the second valve actuation chamber 121b and an opening in the tip of each of the suction pipes 175 forms an opening 175a ,

Three suction pipes 176 are integral with the top wall of the separator plate 179 provided such that they project from the same, wherein the three suction pipes 176 associated with three locations, which are the ends of the lateral and longitudinal spars of the T-shape of the oil collection chamber 174 correspond. Each of these ends of these suction tubes 176 runs to the ceiling of the breather chamber 169 towards and an opening in the end of each of the suction tubes 176 forms a small opening 176a ,

There is also a small opening 180 on the upper wall of the separation box 179 provided, with the small opening 180 a connection between an indentation 179a in the upper surface of the separation box 179 and the oil collection chamber 174 provides.

Furthermore, a pipe 181 that with a the end of the longitudinal spar of the T-shape of the oil collection chamber 174 corresponding surface is integral with the partition plate 165 intended. The end of the pipe 181 is in an inlet 178a of the above oil return passage 178 over a ring seal 182 used, with the inlet 178a into the base of the second valve actuation chamber 121b empties. The oil catch chamber 174 is therefore with the oil return passage 178 connected. The above pipe 181 is in the vicinity of an inner surface of the second valve-actuating chamber 121b arranged and a small opening 181a for sucking oil is provided in the area near the above-mentioned inner surface, wherein the small opening 181a a connection between the second valve actuating chamber 121b and the tube 181 provides.

As the breather chamber 169 with the interior of the air purifier 104 over the breather pipe 170 communicates, the pressure of the breather chamber 169 generally kept at ambient pressure even during operation of the engine E, and the pressure in the second valve actuation chamber 121b that with the breather chamber 169 over the connecting pipe 168 which has a low flow resistance in communication is generally the same as that of the breather chamber 169 ,

Because the crank chamber 106a only the overpressure component of the ascending and descending movement of the piston 115 generated pressure pulses in the Ölzuführrohr 160 through the one-way valve 161 During operation of the engine E ejects, the pressure of the crank chamber 106a a negative pressure on average, and because the second valve actuation chamber 121b , which receives the above-mentioned overpressure, with the breather chamber 169 over the connecting pipe 168 communicating with a small flow resistance is the pressure of the second valve actuation chamber 121b about the same as that of the breather chamber 169 , Because the negative pressure of the crank chamber 106a to the oil tank 104 over the through hole 155 the crankshaft 113 and further to the oil catching chamber 174 via the oil return passage 178 is passed, is the pressure of the oil collection chamber 174 lower than that of the second valve actuating chamber 121b and the breather chamber 169 , and the pressures of the oil tank 140 and the first valve actuating chamber 121 are lower than those of the oil collection chamber 174 ,

As in 22 is shown, therefore, when the pressure of the crank chamber 106a indicated by Pc, the pressure of the oil tank 140 is denoted by Po, the pressure of the first valve-actuating chamber 121 is denoted by Pva, the pressure of the second valve actuation chamber 121b by Pvb, the pressure of the oil-collecting chamber 174 Ps and the pressure of the breather chamber 169 is denoted by Pb satisfying the following relationship. Pvb = Pb>Ps> Po = Pva> Pc

As a result, the pressures of the second valve-actuating chamber become 121b and the breather chamber 169 to the oil collection chamber 174 over the suction pipes 174 and 176 and the small opening 180 passed on, also to the oil tank 140 via the oil return passage 178 passed and then into the crank chamber 106a passed.

An oil mist gets through the oil spills 156a and 156b generates the lubricating oil O inside the oil tank 140 during operation of the engine E stir and squirt, with the oil spinners 156a and 156b through the crankshaft 113 to be turned around. As described above, the oil mist thus generated becomes over part of the timing transmission 122a which is inside the oil tank 140 from the belt guide tube 186 exposed, ie on the drive pulley 123 and a part of the timing belt 125 , sprayed or the oil mist reaches the first valve actuation chamber 121 , and the timing transmission 122a can therefore be lubricated directly. Even if the oil drops over a part of the timing gearbox 122a be sprayed, the oil is not just the entire transmission 122a forwarded, but due to the operation of the timing transmission 122a also to the cam 126 forwarded to lubricate these efficiently.

The one in the oil tank 140 generated oil mist is in the crank chamber 106a over the through hole 155 the crankshaft 113 sucked along the direction of the above-mentioned pressure flow, so the area around the crankshaft 113 and the piston 115 to lubricate. When the pressure of the crank chamber 106 due to a descending movement of the piston becomes an overpressure, the one-way valve opens 161 and the above-mentioned oil mist rises together with that in the crank chamber 106a produced blowby gas through the oil supply pipe 160 and the connection passage 163 upwards, and becomes the second valve-actuating chamber 121b fed to each part of the cam system 122b inside the chamber 121b ie the inlet and exhaust rocker arms 133i and 133e to lubricate, etc.

In this case, a section of the through the above-mentioned connection passage 163 passing oil mist to the oil return passage 178 over the hole-shaped bypass 164 diverted. It is therefore possible, the amount of the second valve actuation chamber 121b supplied oil mist by appropriately adjusting the flow resistance of the bypass 164 adjust.

The oil mist and the blowby gas within the second valve actuation chamber 121b be in gas and liquid by expansion and collision with the labyrinth wall 172 disconnected while going to the breather chamber 169 through the connecting pipe 168 and the gap g around the partition plate 165 around be forwarded, and the blow-by gas is in the engine E via the breather pipe 170 and the air purifier 104 sucked in this order during the intake stroke of the engine E.

Since then, when the engine E is in an upright state, that in the breather chamber 169 liquefied oil in the well 179a in the upper surface of the separation box 179 is present or the connecting pipe 168 flows downwardly or flows through the gap g to at the base of the second valve actuation chamber 121b To remain, the oil is in the oil collection chamber 174 by means of the small opening provided there 180 or the suction tube 175 sucked. Since, when the engine E is in an inverted state, the above-mentioned liquefied oil on the ceiling of the head cover 136 is present, the oil is in the oil collection chamber 174 by means of the suction tube provided there 176 sucked.

The oil sucked in this way in the oil catch chamber 174 returns to the oil tank 140 over the pipe 181 and an oil return passage 178 back. In this case, then, when oil return passage 178 with the oil tank 140 via the first valve actuation chamber 121 is in communication, as in the embodiment shown, from the oil return passage 178 ejected oil via the timing transmission 122a sprayed to lubricate this comfortable way.

As the above breather chamber 169 between the lid of the head cover 136 and the on the inner wall of the head cover 136 attached partition plate 165 is defined and the above-mentioned oil collection chamber 174 between the upper surface of the above separating plate 165 and to the partition plate 165 welded dividing box 179 is defined, the oil collection chamber 174 and the breather chamber 169 in the head cover 136 be provided without the lid of the head cover 136 to share. Since still the breather chamber 169 and the oil catching chamber 174 inside the head cover 136 even if some oil leaks from any of the chamber returns 169 and 174 simply present the oil into the second valve actuation chamber 121b back, without causing any problems, it is not necessary to check if the two chambers 169 . 174 Are oil-tight, and the manufacturing cost can therefore be reduced.

Because the separation box 179 to the partition plate 165 can be welded before the separation plate 165 on the head cover 136 is attached, the oil collection chamber 174 in a simple manner in the separating plate 165 be formed.

Because the oil suction pipes 175 and 176 each integral with the partition plate 165 and the separation box 179 are formed, the Ölsaugrohre 175 and 176 be easily formed.

When the engine E is in an inverted state, as in FIG 23 is shown moves in the oil tank 140 stored oil O to the lid of the tank 140 towards, ie to the side of the first valve actuation chamber 121 , Because the open end of the first valve actuation chamber 121 inside the oil tank 140 is set so that it is at a higher level than the liquid level of the stored oil by means of the belt guide tube 176 , the stored oil O is prevented from entering the second valve actuating chamber 121b penetrates, and it is possible to prevent an excess of oil the timing gearbox 122a is fed, and that a predetermined amount of oil within the tank 140 is maintained to allow the oil spinner 156a and 156b continuously generate oil mist.

When the engine E is in its in operation during its operation 24 As shown, the stored oil moves to the side surface of the oil tank 140 but because of the open end of the first valve actuation chamber 121 inside the oil tank 140 is set to be at a higher level than the liquid level of the stored oil by means of the belt guide tube 186 , the stored oil is prevented from entering the second valve-actuating chamber 121b penetrates, and it is possible to prevent the timing gearbox 122a an excess of oil is supplied, and that a predetermined amount of oil within the oil tank 140 will allow it in this way to allow the slingshots 156a and 156b continuously generate oil mist.

An oil drop guide wall 190 (please refer 15 and 24 ) is integral with the oil tank 140 provided such that they from the inner wall of the oil tank 140 projecting, wherein the oil droplet guide wall 190 the upper side 125a of the timing belt 125 of the timing transmission 122 when facing the drive pulley from the drive side to the output side 123 moved around.

As a result, in the case where the engine E is laid on its side and the upper side, it sticks 25a of the timing belt 125 Moving substantially horizontally from the drive side to the output side, even if that is within the oil tank 140 stored oil below the timing belt 125a is present, a part of by the rotation of the oil slingers 156a . 156b generated Oil mist at the oil drop guide wall 190 The oil collects to form oil drops O 'which are on the upper part of the timing belt 125 fall from the drive side, the oil drops O 'are on the upper side 125a of the timing belt 125 to the side of the driven pulley 124 while being hardly influenced by the centrifugal force, and at the same time, the oil drops O 'move around to the back of the upper side 125a so that they are the driven pulley 124 lubricate reliably.

In this case, if the oil drop guide wall 190 is absent, most of the sticks by the oil slingers 156a . 156b generated oil mist on the lower side of the timing belt 125 On, the oil drops are due to centrifugal force from the timing belt 125 detached when the bottom side of the timing belt 125 around the upper side by turning the drive pulley 123 is driven, and it is difficult for the oil mist, the output side of the timing belt 125 to reach.

The lubrication system of the valve actuating mechanism 122 can therefore be divided into two parts, ie a part for lubricating portions of the cam system 122b and the timing gearbox 122a within the first valve actuation chamber 121 and the oil tank 140 with the inside of the oil tank 140 spilled oil and a part for lubricating the remaining portions of the cam system 122b within the second valve actuation chamber 121b with the second valve actuating chamber 121b forwarded oil mist. The load to be met by each part of the lubrication system may therefore be reduced and the entire valve actuation mechanism 122 can be lubricated reliably. Further, each part of the engine E can be reliably lubricated by the use of the oil drops and the oil mist regardless of the operating position of the engine E.

Since the inside of the oil tank 140 generated oil mist by using the pressure pulses within the crank chamber 106a and the one-way transfer function of the one-way valve 161 is circulated, it is not necessary to use a special oil pump for circulating the oil mist and the structure can be simplified.

Not just the oil tank 140 , but also the oil supply pipe 160 which connects between the crank chamber 106a and the second valve actuating chamber 121b are outside the engine main body 101 is provided, and the weight of the engine E can therefore be reduced to a great extent without interfering with the engine main body 101 which is designed to be thinner and more compact. In particular, the externally arranged Ölzuführrohr 160 hardly by the heat of the engine main body 101 can be influenced and its heat dissipates easily, a cooling of the through the oil supply pipe 160 be promoted passing oil mist.

Furthermore, the oil tank 140 on an outer side of the engine main body 101 is arranged, the overall height of the engine E can be greatly reduced, and since a part of the timing transmission 122a inside the oil tank 140 is housed, any increase in the width of the engine E can be minimized, so that the engine E can be made more compact.

Hereinafter, a second embodiment of the present invention will be described with reference to FIG 25 to 36 explained.

The outer structure of the portable four-stroke engine E will be described with reference to FIG 25 and 26 explained.

A carburetor 202 and an exhaust pot 203 are respectively at the front and rear of the engine main body 201 of the above-mentioned four-stroke portable engine E, and an air cleaner 204 is at the inlet of the carburetor 202 appropriate. A fuel tank made of a synthetic resin 205 is on the lower surface of the engine main body 201 appropriate. The two ends of a crankshaft 213 stand out of the engine main body 201 in front of and an oil tank 240 the one side of the engine main body 201 adjacent and a rewind starter 240 that transmits power with an output element 284 can be connected, which at one end of the crankshaft 213 is attached to the outer surface of the oil tank 240 appropriate.

A cooling fan 243 , which also serves as a flywheel, is at the other end of the crankshaft 213 appropriate. A plurality of fastening approaches 246 (one of them is in 25 shown) are on the outer surface of the cooling fan 243 trained, and a centrifugal shoe 247 is pivotable on each of the attachment lugs 246 stored. These centrifugal shoes 247 form together with a clutch drum 248 , which on a drive shaft described below 250 attached, a centrifugal clutch 249 , and if the speed of the crankshaft 213 exceeds a predetermined value, the centrifugal shoes 247 due to the centrifugal force of the shoes on the inner circumference of the clutch drum 248 pressed so that the output torque of the crankshaft 213 to the drive shaft 250 is transmitted. The cooling fan 243 has a larger diameter than that of the centrifugal clutch 249 ,

An engine cover 251 which the engine main body 201 and its accessories excluding the fuel tank 240 is at appropriate locations on the engine main body 201 attached, and a cooling air inlet 219 is between the engine cover 251 and the fuel tank 205 intended. Outside air is in this way via the cooling air inlet 219 through the rotating cooling fan 243 sucked in and provided for cooling each part of the engine E.

A frustoconical bearing holder 258 , which is coaxial with the crankshaft 213 is located on the engine cover 251 attached, and the storekeeper 258 stores the drive shaft 250 which the cutting device C of the trimmer T (see 1 ) turns over a bearing 259 in the same manner as in the above-mentioned first embodiment.

Because the oil tank 240 and the starter 242 on one side and the cooling fan 243 and the centrifugal clutch 249 are arranged on the other side, wherein the engine main body 201 is arranged between them, the weight balance of the engine E between the right and the left side is improved and the center of gravity of the engine E can be closer to the central part of the engine main body 201 be arranged so that the handling of the engine E is improved.

Further, because the cooling fan 243 having a larger diameter than that of the centrifugal shoes 247 , on the crankshaft 213 between the engine main body 201 and the centrifugal clutch 249 is fixed, it is possible to any increase in the dimension of the engine E due to the cooling fan 243 to avoid.

The structures of the engine main body 201 and the oil tank 240 are below with reference to 25 to 28 . 29 . 32 and 33 explained.

In 25 to 28 contains the engine main body 201 a crankcase 206 with a crank chamber 206a , a cylinder block 207 with a cylinder bore 207a and a cylinder head 208 with a combustion chamber 208a and inlet and outlet channels 209 and 210 which enters the combustion chamber 208a open, and a large number of cooling fins 238 are on the outer circumference of the cylinder block 207 and the cylinder head 208 educated.

The inside of the crank chamber 206a housed crankshaft 213 is in the left and right side wall of the crankcase 206 over ball bearings 214 and 214 ' stored. In this case, the left ball bearing 214 equipped with a gasket and an oil seal 217 is provided so that it is the outside of the right ball bearing 214 ' is adjacent. One in the cylinder bore 207a inserted piston 215 is in a conventional manner with the crankshaft 213 over a connecting rod 216 connected in a common way.

The oil tank 240 is provided so as to be integral with the left wall of the crankcase 206 is formed, and is arranged such that the end of the crankshaft 213 on the side of the sealed ball bearing 214 through the oil tank 240 runs. An oil seal 239 through which the crankshaft 213 runs, is in the outer wall of the oil tank 240 used.

A belt guide tube 286 , which has a flattened cross section, is integral with the ceiling of the oil tank 240 provided, wherein the oil guide tube 286 vertically through the ceiling of the oil tank 240 runs and has an open upper and lower end. The lower end of the belt guide tube 286 runs close to the crankshaft 213 inside the oil tank 240 towards, and the upper end is integral with the cylinder head 208 provided so that it is a separator 285 with the cylinder head 208 Splits. A line of a circular sealing bead 287 is around the circumference of the upper end of the belt guide tube 286 and the cylinder head 208 trained and the separating element 285 stands over the sealing bead 287 in front.

As in 29 . 32 and 33 is shown is a circular sealing groove 288a that the above-mentioned sealing bead 287 corresponds to, in the lower end surface of a head cover 236 formed, and a linear sealing groove 288 which are the two sides of the circular groove 288a Connecting with each other is in the inner surface of the cover 236 educated. A circular pack 239a is in the circular seal 288a used and a linear packing 289b that is integral with the circular packing 289a is formed is in the linear sealing groove 288b used. The head cover 236 is with the cylinder head 208 by means of a bolt 237 connected so that the sealing bead 287 and the separator 285 each in contact with the circular packing 289a and the linear pack 289b be pressed.

The belt guide tube 286 and one half of the head cover 236 form a first valve actuation chamber 221a , where the cylinder head 208 and the other half of the head cover 236 a second valve actuating chamber 221b form, and the two valve actuation chamber 221a and 221b through the above-mentioned separating element 285 shared.

Referring again to 25 to 28 are the engine main body 201 and the oil tank 240 divided into an upper block Ba and a lower block Bb at a plane which is the axis of the crankshaft 213 contains and perpendicular to Axle of the cylinder bore 207a is. That is, the upper block Ba integrally includes the upper half of the crankcase 206 , the cylinder block 207 , the cylinder head 208 , the upper half of the oil tank 240 and the belt guide tube 286 , The lower half Bp integrally includes the lower half of the crankcase 206 and the lower half of the oil tank 240 , These upper and lower blocks Ba and Bb are cast individually and with each other by means of a plurality of bolts 212 (please refer 27 ) after each part has been manufactured.

An inlet valve 218i and an exhaust valve 218e for opening and closing respectively the inlet channel 209 and the outlet channel 210 are in the cylinder head 208 provided such that they are parallel to the axis of the cylinder bore 207 run and a spark plug 220 is screwed in such that its electrodes are near the central region of the separation chamber 208a lie.

A valve actuating mechanism 222 for opening the above intake valve 218i and exhaust valve 218e is below with reference to 26 to 30 explained.

The valve actuating mechanism 222 includes a timing transmission 222a which is from the inside of the oil tank 240 to the first valve actuating chamber 221a runs, as well as a cam system 222b which is from the first valve actuation chamber 221a to the second valve actuating chamber 221b runs.

The timing transmission 222a includes a drive pulley 223 attached to the crankshaft 213 inside the oil tank 240 attached, an output pulley 224 which is rotatable in the upper half of the belt guide tube 286 is stored, and a timing belt 225 , that around this drive and driven pulley 223 and 224 is wound. On the side of the separator 285 is the end face of the driven pulley 224 integral with a cam 226 connected, which is part of the cam system 222b forms. The cam 226 is therefore common with the driven pulley 140 on one side of the cylinder head 208 arranged. The drive and driven pulley 223 and 224 are provided with teeth, and the drive pulley 223 drives the driven pulley 224 over the belt 224 with a reduction ratio of 1: 2.

A warehouse wall 227 is integral with the outer wall of the belt guide tube 186 formed, with the bearing wall 227 within the circular sealing bead 287 rises and is in contact with or near the inner surface of the head cover 236 located, and by means of a through hole 228a which is in the warehouse wall 227 is provided, and a bottomed hole 228b which is in the separating element 285 is provided, both ends of a bearing shaft 229 rotatably mounted, and the above driven pulley 236 and the cam 226 are rotatable in the middle part of the bearing shaft 229 stored. Before the head cover 236 is attached, the bearing shaft 229 from the through hole 228a in a shaft hole 235 the driven pulley 224 and the cam 226 and in the blind hole 226b introduced. After insertion, the head cover 236 on the cylinder head 238 and the belt guide tube 286 attached so that the inner surface of the head cover 236 the outer end of the bearing shaft 229 opposite to as a stop for the bearing shaft 229 to act.

A pair of bearing approaches 230i and 230e parallel to the bearing shaft 229 project, are integral with the separator 285 on the side of the second valve actuating chamber 221b educated. The cam system 229b includes the above cam 226 , an intake rocker arm shaft 231i and an exhaust rocker arm shaft 231e , which are rotatable respectively in the above bearing lugs 230i and 230e are stored, an intake cam follower 2321 and an exhaust cam follower 232e , each at one end of the rocker shaft 233i and 233e within the first valve actuation chamber 221a are attached, wherein the front end of both the intake cam follower 232i as well as the exhaust cam follower 232e in sliding contact with the lower surface of the cam 226 located, an intake rocker arm 233i and an exhaust rocker arm 233e , respectively at the other end of the intake and exhaust rocker shaft 233i and 233e are mounted within the second valve actuating chamber 221 wherein the front end of both the intake rocker arm 233i as well as the exhaust rocker arm 233e in contact with the upper end of both the inlet valve 218i as well as the exhaust valve 218e is located, and wherein an inlet spring 234i and an exhaust spring 234e each at the inlet valve 218i and the exhaust valve 218e are attached and apply the same in the closing direction.

The bearing shaft 229 and the intake and exhaust rocker arms 231i and 231e are above the circular sealing bead 287 at the top of the cylinder head 208 and the belt guide tube 286 arranged.

When the crankshaft 213 turns, turns together with the crankshaft 213 rotating drive pulley 213 and the driven pulley 224 and the cam 226 over the belt 225 , the cam 226 then tilts the intake and exhaust cam followers 232i and 232e with a suitable timing, with the tilting movements to the inlet and Auslasskipphebelarme 233i and 233e over the corresponding rocker arm shafts 231i and 231e and tilted intake and exhaust rocker arms in this manner 233i and 233e can the intake and exhaust valves 218i and 218e with an appropriate timing open and close while using the inlet and outlet springs 234i and 234e interact.

Because in the timing transmission 222a the driven pulley 224 and the cam 226 rotatable by the bearing shaft 229 are stored and the bearing shaft 229 also in both side walls of the first valve actuation chamber 221a is rotatably mounted, rotates the bearing shaft 229 due to frictional resistance during rotation of the driven pulley 224 and the cam 226 where the difference in speed between the bearing shaft 229 and the driven pulley 224 and the cam 226 decreases and erosion of the rotating and sliding areas can be suppressed to increase the life.

The cam 226 which has a comparatively large diameter is on a side of the cylinder head 108 together with the driven pulley 224 arranged, and only the inlet and Auslasskipphebelarme 233i and 233e and the intake and exhaust rocker shafts 231i and 231e which have a comparatively small diameter are immediately above the cylinder head 208 arranged. The valve actuating mechanism 228 Therefore, does not take a large volume above the cylinder head 208 and it is possible to reduce the overall height of the engine E, thereby making the engine E more compact.

Furthermore, the bearing shaft 229 and the intake and exhaust rocker shafts 231i and 231e arranged at a higher position than that of the line of the circular Abdichtwulst 287 at the top of the cylinder head 208 and the belt guide tube 286 , it is therefore possible the bearing shaft 229 and the intake and exhaust rocker shafts 231i and 231e above the sealing bead 287 without any hindrance of the same in a state in which the head cover 236 is removed, assembled and disassembled, and the installation and maintenance is extremely easy to carry out.

The lubrication system of the above-mentioned engine E will be described below with reference to FIG 26 to 34 explained.

As in 27 and 28 is shown, the lubrication system of the engine E includes a first lubricating part La for lubricating the area around the crankshaft 213 around, ie the crankshaft 213 , the storage 214 and 214 ' , the connecting rod 216 , the piston 215 , etc., and a second lubricating part Lb for lubricating the valve operating mechanism 222 , These parts La and Lb share the above oil tank 240 , The oil tank 240 stores a predetermined amount of lubricating oil O passing through an oil inlet 240 is poured. A pair of slingshots 256a and 256b on each side of the drive pulley 223 are arranged in the axial direction are by a press fit on the crankshaft 213 attached. These slingshots 256a and 256b extend in directions radially opposite to each other and the front ends thereof are bent so as to move away from each other in the axial direction, so that when the oil spinner 256a and 256b through the crankshaft 213 be turned, at least one of the slingshots 256a and 256b that within the oil tank 240 Stored oil is stirred and sprayed so as to produce an oil mist regardless of the operating position of the engine E.

The lubrication system La includes a first oil passage 2601 that by the crankshaft 213 is provided and a connection between the interior of the oil tank 240 and the crank chamber 206a and a second oil passage 2602 that makes a connection between the base of the crank chamber 206a and the interior of the oil tank 240 provides, and a first one-way valve 261 is at the opening of the second oil passage 2602 in the crank chamber 206a intended. The first one-way valve 261 closes and opens when the pressure of the crank chamber 206a with the ascending and descending motion of the piston 215 reduced and increased. The first and second oil passages 2601 and 2602 are formed such that their open ends 2601a and 2602a inside the oil tank 240 as close as possible to the middle part of the oil tank 240 lie, with an arrangement such that the open ends 2601a and 2602a always above the liquid level of the stored oil, regardless of the operating position of the engine E.

The second lubrication system Lb includes a third oil passage 2603 passing through the engine main body 201 is provided so that it connects between the middle part of the first valve actuating chamber 221a and the base of the second valve actuating chamber 221b provides a collection chamber 274 in the head cover 236 is formed such that it communicates with the second valve actuating chamber 221b communicates, a fourth oil passage 260a in the engine main body 201 is provided so that it connects between the oil collection chamber 274 and the crank chamber 206a provides the second oil passage 2602 and a second one-way valve 262 at the opening of the third oil passage 2603 in the second valve actuating chamber 221b is provided. The second one-way valve 262 closes and opens when the pressure of the crank chamber 206a with the ascending and descending motion of the piston 215 each reduced and increased.

As in 28 . 32 and 33 is shown is a separation plate 265 containing a breather chamber 269 defined in the upper part of the head cover 236 on the ceiling of the cover 236 by means of a plurality of support struts 266 and on the struts 266 attached to fixed brackets, with the support struts 266 are provided so that they protrude from the ceiling. The breather chamber 269 communicates with the second valve actuating chamber 221b on one side over a large gap in connection, ie a connecting pipe 268 (please refer 32 ) between the periphery of the partition plate 264 and the inner wall of the head cover 236 , and stands with the air purifier 204 on the other side via a breather pipe 270 in connection. The mixture of oil and blowby gas is in gas and liquid and deaerator chamber 269 separated.

To the partition plate 265 is a box-shaped separator 279 welded, which is the above-mentioned oil collection chamber 274 in the room on the upper surface of the partition plate 265 forms.

A plurality of suction pipes 275 (four in the illustrated embodiment) are integral with the separator plate 265 provided so that they protrude from the same, wherein each of the suction pipes 275 separated from the others and with the oil catching chamber 274 communicates. The end of each of the suction pipes 275 extends to the vicinity of the base of the second valve actuating chamber 221 and an opening in each end forms a small opening 275a ,

A plurality of suction pipes 276 (three in the illustrated embodiment) are integral with the top wall of the separator plate 279 provided so that they protrude from the same, each of the suction tube 276 separated from the others and with the oil collection chamber 274 communicates. The end of each of these suction tubes 276 runs close to the ceiling of the breather chamber 269 and an opening in each end forms a small opening 276a ,

There are also small openings 280 and 283 each in the partition plate 265 and the separation box 279 provided, with the small openings 280 and 283 the oil catchment chamber 274 each with the second valve actuation chamber 221b and the breather chamber 269 connect.

Furthermore, a pipe 281 that with the oil collection chamber 274 communicates, integral with the partition plate 265 provided that it projects from the same. The top of the pipe 281 is at the top of the fourth oil passage 260a over a ring seal 282 connected, wherein the upper end of the fourth oil passage 260a is opened so that it from the base of the second valve actuation chamber 221b protrudes. The oil catch chamber 274 is this way with the fourth oil passage 260a connected.

The effect of the lubrication system of this engine E will be explained below. Because the oil spinners 256a and 256b , which work together with the crankshaft 213 turn that in the oil tank 240 Stirring stored oil during operation of the engine and spraying it to produce an oil mist are the oil tank 240 and the first valve actuating chamber 221a placed in the upper part of the oil tank 240 open, filled with oil mist. The timing transmission 222a that within the first valve actuation chamber 221 is therefore lubricated directly with the oil mist.

The pressure pulses where the pressure is due to the ascending and descending motion of the piston 215 repeatedly reduced and increased, occur in the crank chamber 206a on. Along with these pressure pulses is that in the oil tank 240 generated oil mist between the oil tank 240 and the crank chamber 206a passed back and forth, and in the crank chamber 206a generated oil mist lubricates the area around the crankshaft 213 ie the crankshaft 213 , camps 214 and 214 ' , the connecting rod 216 , the piston 215 etc. As the first one-way valve 261 closes when the pressure of the crank chamber 206a decreases, and opens when the pressure rises, and a part of the overpressure component of the pressure pulses in this way in the oil tank 240 over the second oil passage 2602 is ejected when the oil mist is in the crank chamber 206a liquefied and at the base of the chamber 206a remains, the oil in the oil tank 204 over the second oil passage 2602 pushed back together with the above-mentioned overpressure.

The pressure pulses within the crank chamber 206a also affect the second one-way valve 262 over the oil tank 240 , the first valve actuating chamber 221a and the third oil passage 2603 , and the second one-way valve 262 also closes when the pressure of the crank chamber 206a decreases and opens when the pressure rises. If the second one-way valve 262 opens, the oil mist is inside the oil tank 240 sequential to the first valve actuation chamber 221a , to the third oil passage 2603 and to the second valve actuating chamber 221b forwarded. In the meantime, the oil mist lubricates the timing gearbox 222a in the first valve actuating chamber 221a and the cam system 222b in the second valve actuating chamber 221b ,

Since the overpressure component of the pressure pulses in the crank chamber 206 in the oil tank 240 over the first one-way valve 261 is ejected, and the pressure in the crank chamber 260a On average, there is a negative pressure, and so is the pressure of the oil-collecting chamber 274 that with the crank chamber 206a over the fourth oil passage 260a communicates, a negative pressure. On the other hand, the breather chamber 269 with the interior of the air purifier 204 over the breather pipe 270 communicates and the pressure of the breather chamber 269 Generally, even during operation of the engine is kept at ambient pressure, the pressure of the second valve actuation chamber 221b that with the breather chamber 269 over the connecting pipe 268 is also generally ambient pressure. As a result, the pressures of the second valve-actuating chamber become 221b and the breather chamber 269 to the oil collection chamber 274 over the suction pipes 275 and 276 and the small openings 280 and 283 forwarded and the oil mist within the second valve actuation chamber 221b and the breather chamber 269 also gets to the oil catching chamber 274 accompanying this movement in the pressure. In particular, while the engine E is in an upright state, it becomes in the second valve actuating chamber 221b liquefied and in the base thereof remaining oil to the oil collection chamber 274 by means of the oil suction pipe 275 , which is near the base of the second valve actuation chamber 221b is arranged, forwarded. While the engine E is in an inverted state, it will be in the breather chamber 269 liquefied and in the base thereof, ie the ceiling of the head cover 236 oil located to the oil collection chamber 274 by means of the oil suction pipe 276 which is near the ceiling of the head cover 236 is arranged, forwarded. This way in the oil catching chamber 274 recovered oil gets into the crank chamber 206a over the fourth oil passage 206a forwarded to the area around the crankshaft 213 to lubricate.

The timing transmission 222a and the cam system 222b , which have a comparatively low load, are only lubricated with the oil mist, which in the first and second valve actuation chamber 221a and 221b from the oil tank 240 is introduced, wherein the amount of lubricating oil is relatively low and excessive lubrication can be avoided. The surrounding areas of the crankshaft 213 are lubricated with the oil mist that enters the crank chamber 206a from the oil tank 240 is introduced, and the oil mist and the liquefied oil are in the oil collection chamber 274 after lubrication of the cam system 222b recovered. The amount of lubricating oil is comparatively large and it is possible the area around the crankshaft 213 which is subjected to a comparatively high load to lubricate efficiently. Because the surroundings of the crankshaft 213 and the valve actuating mechanism 222 can be lubricated according to their load, the amount of circulating oil, ie the amount of within the oil tank 240 stored oil can be reduced in comparison with the conventional system, and the oil tank 240 and therefore the entire engine E can be made more compact and lighter.

Since the inside of the oil tank 240 generated oil mist by using the pressure pulses within the crank chamber 206a and the one-way transfer functions of the first and second one-way valves 261 and 262 is circulated, it is not necessary to provide a special oil pump for circulating the oil mist and the structure can be simplified.

That in the crank chamber 206a generated blowby gas becomes the oil tank 240 over the first oil passage 2601 and to the breather chamber 269 together with the oil mist over the first valve actuation chamber 221a , the third oil passage 2603 and the second valve actuating chamber 221b transferred, they are in the gas and liquid in the breather chamber 269 separated and separated from the oil blow-by gas is in the engine E via the breather pipe 270 and the air purifier 204 sucked in this order during the intake stroke of the engine E.

If the engine E, as in 35 shown is reversed or, as in 36 is shown, this moves in the oil tank 240 stored oil to the ceiling or the side surface of the oil tank 240 out. However, because the open end of the first valve actuation chamber 221 to the oil tank 240 is set so that it is always at a higher level than the liquid level of the stored oil O by means of the belt guide tube 286 , the stored oil O is prevented from the first valve-operating chamber 221a achieved, and it is possible to prevent excess oil from the timing gearbox 222a is supplied, and a predetermined amount of oil within the tank 240 is maintained so as to allow the oil spinners 256a and 256b continuously produce an oil mist.

Because the oil tank 240 on the outside of the engine main body 201 is arranged, the overall height of the engine E can be greatly reduced, and a part of the timing transmission 226a inside the oil tank 240 is accommodated, any increase in the width of the engine E can be minimized to make the engine E more compact and lighter.

In the above-mentioned third embodiment, the third oil passage is 2603 with the middle part of the first valve actuating chamber 221a connected, the third oil passage 2603 can with the upper part of the first valve actuation chamber 221a be connected.

Each of the above embodiments uses a belt type timing transmission, but a chain type timing transmission can be used.

In a four-stroke portable engine, a valve operating mechanism includes a camshaft rotatably supported in a cylinder head to open and shoot intake and exhaust valves, and a timing transmission disposed on a side outside of the engine main body and a connection between a crankshaft and the camshaft and a power output centrifugal clutch is mounted on the crankshaft on the opposite side outside of the engine main body. The timing transmission and the centrifugal clutch, which are arranged at the two ends of the crankshaft, improve the weight balance, wherein the center of gravity of the engine may be formed as close as possible to the central part of the crankshaft, which, together with the reduced weight, increases the manageability of the engine.

Claims (12)

A four-stroke portable engine comprising an engine main body, wherein the engine main body includes a crankcase having a crank chamber, a cylinder block having a cylinder bore and a cylinder head having an intake port and an exhaust port, a crankshaft supported in the crankcase and received in the crank chamber, a cylinder bore and a piston connected to the crankshaft, an intake valve and an exhaust valve for opening and closing the intake port and the exhaust port, wherein the intake valve and the exhaust valve are mounted in the cylinder head, a valve operating mechanism operable in association with the rotation of the crankshaft around the intake valve and opening and closing the exhaust valve, and a power output mechanism provided at one end of the crankshaft protruding from the engine main body, wherein the valve operating mechanism comprises a rotatable member in the cylinder A crankshaft mounted to the crankshaft to open and close the intake valve and the exhaust valve, and a timing gear which is arranged outside of the engine main body on the opposite side of the power output mechanism, is connected to one end of the crankshaft, and an association between the crankshaft and the camshaft a cam system for transmitting the rotational force of the output side of the timing transmission to the intake and exhaust valves for opening and closing forces, a first valve operating mechanism chamber accommodating the timing gear, a second valve operating mechanism chamber accommodating at least a part of the cam system and formed in the cylinder head ; and characterized in that the first valve-operating mechanism chamber is provided integrally with an oil tank disposed outside the engine main body on the same side as the timing transmission; and that a pair of oil slingers for mixing and atomizing oil stored in the oil tank to produce an oil mist to be supplied to the second valve operating chamber and the crank chamber are fixed to the crankshaft in such a manner that the timing transmission between the pair of Slingshot is arranged. The portable four-cycle engine according to claim 1, wherein a flywheel is disposed on the crankshaft between the engine main body and the power output mechanism, wherein the flywheel includes cooling blades for conveying cooling air to the engine main body and has a larger diameter than that of the power output mechanism. The portable four-cycle engine according to claim 1, wherein there is provided in the crankshaft a through hole through which the oil mist generated in the oil tank is supplied to the crank chamber, and wherein an open end of the through hole is disposed in the oil tank between the timing transmission and an oil slinger. The portable four-cycle engine according to claim 1, wherein the oil tank for storing the lubricating oil and the timing gear of the valve operating mechanism are disposed on one side of the engine main body, wherein the timing transmission extends into the oil tank, wherein a timing transmission receiving belt guide tube is provided integrally with the oil tank and wherein the open end of the belt guide tube projecting within the oil tank to the central part of the oil tank, so that the open end, regardless of whether the engine is upside down or on the side, above the liquid level of the stored oil. The portable four-cycle engine according to claim 1, wherein the oil tank, one end of the crankshaft extending into the oil tank and the oil tank Timing gear of the valve operating mechanism, which is connected to the crankshaft within the oil tank, are arranged outside of the engine main body on the side opposite to the power output mechanism and the timing gear is lubricated by the oil within the oil tank. The four-stroke portable engine according to claim 5, wherein a cooling fan is fixed to the crankshaft between the engine main body and the power output mechanism, the cooling fan having a diameter larger than that of the power output mechanism. A portable four-cycle engine according to claim 1, wherein the timing gear of the valve operating mechanism is constructed as a Umgriffstyp with a Umgriffselement, wherein the drive side of the Umgriffselements extends into the oil tank, wherein an oil mist generating means for generating an oil mist for lubricating the timing transmission by atomizing oil stored within the oil tank is provided in the oil tank, and wherein an oil drop guide wall is provided so as to protrude from the inner wall of the oil tank, wherein the oil drop guide wall leads the adhering oil drops onto the part of the timing gear extending into the oil tank and drips when the engine is on the side lies. Portable four-stroke engine according to claim 1, wherein the valve operating mechanism is provided above an oil tank disposed outside of the engine main body and storing oil, a first valve actuating chamber being arranged to extend upwardly from the oil tank, and a second valve actuating chamber formed in the cylinder head, wherein the oil tank and the crank chamber communicate with each other via a through-hole, wherein the crank chamber and the second valve actuating chamber communicate with each other by means of an oil supply pipe provided outside the engine main body, wherein the second valve actuating chamber and the oil tank communicate with each other by means of an oil return passage, wherein the oil tank comprises an oil mist generating means, namely the pair of oil spinners, for generating an oil mist by mixing and atomizing the stored oil, and wherein transfer means for transferring the oil mist within the oil tank to the oil supply pipe via the crank chamber is connected to the oil supply pipe so that the valve operating mechanism within the first valve operating chamber is lubricated with the oil atomized inside the oil tank, and wherein the valve actuating mechanism is lubricated within the second valve actuation chamber with the oil mist transferred from the oil feed tube to the second valve actuation chamber. A four-stroke portable engine according to claim 8, wherein the transfer means includes a valve means which closes the oil supply pipe when the pressure of the crank chamber is a negative pressure, and the pipe opens when the pressure is a positive pressure. A portable four-cycle engine according to claim 8 or 9, wherein the oil supply pipe and the oil return passage are connected to each other via a bypass. Portable four-stroke engine according to claim 1, wherein the valve operating mechanism includes the timing gear having a rotating input member connected to the crankshaft, and includes a cam system for transmitting the rotational force of a rotating output element of the timing transmission to the intake valve and the exhaust and opening force discharge valve; wherein a first valve actuating chamber and an oil tank are provided on one side of the engine main body, the first valve actuating chamber containing the timing gear, the oil tank with oil mist generating means for generating an oil mist of stored oil, namely the pair of oil spinners, and the lower end opening within the oil tank contains the first valve actuating chamber, wherein a second valve-operating chamber accommodating the cam system is provided in the upper part of the engine main body so as to be aligned with the first valve-operating chamber, wherein a first lubrication system comprises first and second oil passages arranged side by side with each other and providing communication between the oil tank and the crank chamber, and a first oil supply means for circulating the oil mist generated inside the oil tank from the oil tank via the first oil passage, the crank chamber and the second oil passage back to the oil tank, and wherein a second lubrication system comprises a third oil passage that provides communication between the first valve-operating chamber and the second valve-actuating chamber, a fourth oil passage providing communication between the second valve actuating chamber and the crank chamber, the second oil passage and a second oil supply means for circulating the oil mist generated inside the oil tank from the oil tank via the first valve operating chamber, the third oil passage, the second valve actuating chamber, the fourth oil passage, the crank chamber and the second oil passage back to the oil tank. The portable four-cycle engine according to claim 11, wherein the first oil supply means comprises a first one-way valve provided in the second oil passage and closes when the pressure of the crank chamber decreases, and that opens when the pressure rises, and wherein the second oil supply means second one-way valve, which is provided in the third oil passage and closes when the pressure of the crank chamber decreases, and that opens when the pressure increases.

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